Effect of soil condition on seismic response of isolated base buildings

In the present paper, nonlinear time history and response spectrum analyses were carried out using Etabs-2015 software to study the influence of soil condition beneath the isolated base. The effects of soil flexibility are considered in the current study to examine the differences in spectral acceleration, base shear, story displacements, story drifts and story shear obtained following the seismic provisions of Indian standard code. Various soils are systematically compared and discussed for a seismic performance of multistory buildings. Parametric analysis of the buildings fitted with isolation devices is carried out to choose the appropriate type of soil. The study shows that the value of base shear increases with an increase of soil flexibility and superstructure stiffness. It also observed that the spectral acceleration (SA) and spectral displacement (SD) are higher in soft soil condition, which gives us evidence that the response spectral of a structure is associated with soil condition. The paper concluded that the hard soil and medium soil are suitable for base isolation building. In addition, analysis and design considerations for base isolated and conventional structures are suggested to enable the designer to get a better understanding at the preliminary design stage